Brain natriuretic peptide is a hormone produced by the heart with vasodilating and diuretic properties. Previous studies in patients with stable congestive heart failure (CHF) indicate that administration of exogenous brain natriuretic peptide has short-term favorable effects on the heart and kidneys, even in patients with decompensated heart failure treated for up to six hours. The current study is being undertaken to determine the critical safety of 24-hour infusion of two doses of human brain natriuretic peptide (Natrecor) compared to dobutamine in patients with decompensated heart failure. A secondary safety assessment will permit continued therapy for up to seven days.